ABSTRACT
A method was developed for analyzing the stable carbon isotope ratio of five volatile components ( Ethanol, Glycerol, Acetic acid, Ethyl lactate, 2-methyl-butanol ) in wine using gas chromatography-combustion-isotope ratio mass spectrometer ( GC-C-IRMS ) . The sample injection volume was less than 0. 5 μL, and the analytical time of each run was less than 14 min. The precision of this method was 0. 08‰-0. 25‰ for analyzing standards, while 0. 09‰-0. 36‰ for wine samples. Compared to element analysis-isotope ratio mass spectrometry ( EA-IRMS) results, the deviations were lower than 0. 5‰. Fifty-four wine samples from France, Australia, America and China were considered. The δ13 C of five volatile components were measured using GC-C-IRMS. Discriminant analysis ( DA) was employed for analyzing the geographical origin traceability of selected wine. The result indicated that δ13 C of volatile components could be used to distinguish the origin of wines. The method was shown to be effective in improving detection of the origin traceability of wine.
ABSTRACT
Objective To explore MR imaging features of synovial chondromatosis,and evaluate the diagnostic value of MR imaging.Methods The imaging data of 16 cases with pathologically confirmed synovial chondromatosis were analyzed retrospectively,who underwent the preoperative X-ray plain film and MR plain-scan and enhanced-scan.Two cases of should joint,4 cases of hip joint,8 cases of knee joint(ten joints),2 cases of ankle joint.Results Eleven cases (13 joints) were truly diagnosed according to X-ray plain film,the typical features of synovial chondromatosis were hyperdense free bodies in the joint space and adjacent soft tissue,which showed the concentric lamina sign.Fourteen cases (16 joints) were truly diagnosed according to MR imaging,which clearly showed thickened synovium with significant enhancement,multiple intraarticular cartilage or bony nodules with the surface enhanced,and some nodules connected with thickening synovial membrane,joint effusion and joint degeneration.MR could display the synovial abnormalities that could not be displayed in X-ray plain film,which was helpful to distinguish the characteristics of free bodies in joint,and superior to X-ray plain fdm in showing the lesions in detail.Conclusion MR could clearly show the synovial abnormalities and free body in the joints,which has important value for the diagnosis of synovial chondromatosis,determination of the extent of lesions and the characteristics of free body.
ABSTRACT
A method for the determination of seven kinds of thiocarbamate herbicides, molinate, pebulate, vernolate, triallate, thibencarb, eradicane and butylate in black tea and green tea has been developed. After homogenization, 2.0 g tea sample was soaked with 6 mL water for 1 h. 2.5 g NaCl was then added, and the sample was extracted twice by 20 mL acetonitrile. After concentration, the extract was put through HLB column and eluted by 3 mL acetonitrile. The eluate was then concentrated and dissolved with 2.0 mL hexane-acetone (7∶ 3, V/V) mixture. The preparation was cleaned by Envi-Carb column and eluted with 5 mL hexane-acetone. After concentration, the residue was dissolved by acetonitrile-water (5∶ 5, V/V) solution. Detection was achieved by electrospray ionization(ESI) in positive mode using multiple reaction monitoring. D_3-carbaryl was used as the internal standard, the linear range for the herbicides was 0-200 μg/L and the limit of detection were from 0.093 to 1.77 μg/L, with the correlation coefficients(r) varying from 0.9954 to 0.9988. The recoveries of all thiocarbamate herbicides were from 77.3% to 91.5% at the spiked levels of 5-20 μg/kg. The RSD of each compound was less than 15%. Black tea and green tea samples were successfully analyzed by the proposed method with satisfactory results.
ABSTRACT
The operating principle of data acquisition section of TOSHIBA Aquilion 16 is introduced.The operating principles of the main detector,the reference detector,the data acquisition section and its power supply are analyzed.The troubleshooting methods for DAS are put forward.